Transcription

1 Page 1 of 5 Traveler Information TYPHOID GENERAL INFORMATION Introduction Typhoid fever and paratyphoid fever are bacterial infections of the intestinal tract. Typhoid is caused by Salmonella typhi and paratyphoid by Salmonella paratyphi, which belong to the larger group called Salmonella enterica (S. enterica), bacteria that cause enteric fevers (intestinal illness). Worldwide, there are about 30 million cases of enteric fever annually, occurring mainly in countries with poor standards of hygiene. Disease occurs when one eats or drinks contaminated food or water. Vaccines are available for typhoid but not for paratyphoid. Mode of Transmission Enteric fevers are spread via food and water that is contaminated with fecal matter from an infected human carrier. Typhoid can also be transmitted by person-to-person contact, especially through food handlers. Epidemiology The enteric fevers are endemic in most of the developing world. Prevalence is highest in countries with warm climates and less developed sanitary facilities for sewage disposal and water treatment. In highly industrialized countries, enteric fevers occur sporadically or as imported cases. There have been small outbreaks in industrialized countries, such as in the popular tourist resort of Zermatt, Switzerland, where the town's water supply was contaminated in Risk is highest for travelers to southern Asia (India, Nepal, Pakistan, Bangladesh). Other areas of risk include East and Southeast Asia, the Caribbean, Central and South America, and sub- Saharan Africa. Risk is moderate on typical southern African safaris (e.g., South Africa, Botswana, Zambia). Risk in Mediterranean resorts and Eastern Europe has declined steadily. Risk Factors Eating or drinking contaminated food or water is the main risk factor for infection. The risk of acquiring clinical disease following infection varies with the number of organisms ingested and the health of gastric acid secretion. Gastric acid is the body's first line of defense against this disease. The risk of contracting an enteric fever may be increased by taking drugs that suppress gastric acid (e.g., antacids, H2-antagonists, and proton pump inhibitors) or by vagotomy (surgical cutting of the vagus nerve in order to reduce acid secretion in the stomach). In general, travelers to industrialized countries are at little, if any, risk of contracting typhoid. As noted above, typhoid is common in most developing countries. Risk is highest in Nepal, Pakistan, India, Bangladesh, and Southeast Asia. Risk also exists in most other developing countries, particularly countries in Africa, Central and South America, south Asia, and parts of Indonesia.

2 Page 2 of 5 School-aged children are at a higher risk of contracting the disease, although it is not as severe in children younger than age 2 years. In any endemic country, even the most hygienic restaurant may be risky because of a typhoid carrier. Transmission is highest in the dry season and at the beginning of the rains. Symptoms Fever is the main symptom, leading gradually to abdominal pain and diarrhea. If untreated, this disease can be fatal. Fever begins gradually after an incubation period of 1-3 weeks, followed by headache, fatigue, diarrhea, abdominal pain, and red spots on the abdomen. In severe cases, mental confusion, shock, and intestinal bleeding can occur. Need for Medical Assistance Any traveler who develops fever, malaise, and diarrhea after or during travel in the tropics should seek medical assistance. PREVENTION Primary Protection Measures Standard precautions to avoid contaminated food and drink should be observed. (See the article Food and Beverage Precautions.") In areas with poor sanitation and hygiene, one should assume that canned or bottled carbonated drinks, beer, wine, and beverages made with boiled water are the only safe drinks. In some places the possibility exists that commercial water bottles may have been filled with tap water and recapped; therefore, carbonated bottled water is the safest option (although some brands may be high in sodium). Travelers in risk areas should always avoid ice cubes. Alcohol will not make mixed drinks made with plain tap water safe. Non-disposable glasses and cups should be considered unsafe, as well. Travelers should drink from the original beverage containers using sanitary straws. Water should be boiled for hygienic purposes such as brushing teeth and washing near themouth. Some travelers may wish to bring an inexpensive immersion coil along for boiling water. If bottled carbonated water is not available and boiling is not practical, the best alternative is to treat water with either iodine additives or tetracycline hydroperiodide tablets. Cloudy water should be filtered through a clean cloth or coffee filter to remove sediment before treating. Food presents risks as well. Travelers to risk areas should avoid leafy and uncooked vegetables and salads. Fruits, nuts, and vegetables are probably safe if they are well cleaned and have an intact thick skin or shell, which should be peeled, taking care not to contaminate the inside. Meats, fish, and other seafood should be cooked well done and served piping hot. Bread is safest when served fresh from the oven. Moist grain dishes (like rice) that have been allowed to sit at room temperature for prolonged periods should be avoided. Other foods to avoid include cold meat platters, mayonnaise, and creamy desserts, as well as buffets and products from street vendors. Unpasteurized dairy products, including cheese and yogurt, should not be

3 Page 3 of 5 consumed. To protect against any attempts by local vendors to "stretch" pasteurized milk by adding water or unpasteurized milk to cartons or bottles, travelers should stick to drinking canned milk. Other preventive measures: Travelers should not swim or fish in polluted waters and should not eat fish that may have been caught in polluted waters. Travelers should wash their hands frequently, especially before eating. Vaccination Vaccines are available for typhoid (but not paratyphoid) and are recommended for the majority of travelers to endemic countries. Vaccine is about 70% protective in people living in endemic areas. Protection may last longer with the oral vaccine. Rates of protection have not been measured in travelers but might be higher because hygienic eating habits should reduce the number of typhoid organisms ingested. There are 2 types of typhoid vaccines available in the U.S.: a live oral vaccine and an inactivated" (killed) injectable vaccine. Typhoid vaccine is not recommended for all international travelers. Because typhoid vaccines are not 100% protective, it is important to follow proper food and beverage precautions (see above). If a large amount of the typhoid bacteria is ingested, the protection offered by the vaccines becomes minimal. However, because the illness has the potential to be very serious, vaccination is well worth consideration for travelers who will be at high risk. Who Should Receive the Vaccine Travelers should receive typhoid vaccine if traveling to developing countries, because typhoid fever is moderately to highly endemic in nearly all developing countries. Risk is greatest for travel to India, Pakistan, Nepal, Bangladesh, and Southeast Asia. Risk exists in most other developing countries, as well, particularly in Africa, Central and South America, south Asia, and parts of Indonesia. In risk areas, the need for vaccination is greatest for long-stay travelers, persons with adventurous eating habits, and persons who travel outside of pre-arranged, fixed itineraries (including common tourist packages), especially in rural areas. As access to reasonable medical care decreases, the importance of vaccination increases. Other countries may have some risk of typhoid associated with risk behaviors (listed above) and travelers should be vaccinated if they fit into these risk categories or if you desire maximum pre-travel protection. Travelers should observe careful food and water precautions regardless of vaccination status. Note: These recommendations reflect a synthesis of available advice from the Centers for Disease Control (CDC), the CDC's Advisory Committee on Immunization Practices (ACIP), American Academy of Pediatrics (AAP), and the World Health Organization (WHO), as well as ongoing global surveillance and the published literature; these recommendations may differ from those of individual countries' public health authorities. Who Should Not Use the Vaccine As a general rule, some people should not be vaccinated unless the benefit of the vaccine clearly outweighs the

4 Page 4 of 5 disease risk. People suffering from a moderate or severe illness (with or without fever) should delay vaccination until they have recovered. Oral vaccine Pregnant women: Because this is a live-bacteria vaccine and there is at least theoretical reason to be concerned about its effect on a developing fetus, pregnant women should receive this vaccine only when the journey is necessary and the risk of contracting the disease is so substantial as to outweigh the theoretical risk to the fetus. Oral typhoid vaccine should not be given to: children less than 6 years of age persons with altered immune status, including those with AIDS persons with acute diarrhea or vomiting travelers receiving sulfa medications and antibiotics (see "Timing" for information on taking oral typhoid and antimalarial drugs) people with a history of prior severe reaction to this vaccine Injectable vaccine Pregnant women: Because the effect of this vaccine on the fetus is unknown, pregnant women should receive this vaccine only when the journey is necessary and the risk of contracting the disease is so substantial as to outweigh any possible risk to the fetus. This vaccine should not be given to: children less than 2 years of age persons who have had a prior severe reaction to this vaccine The vaccine's effectiveness could be lowered in persons with immune disorders or those receiving treatment that lowers their immunity. Persons with any bleeding disorder should discuss with their health provider their options for receiving this vaccine, because it is given intramuscularly. Risks and Side Effects Oral vaccine: Side effects from the oral vaccine are rare; when they do occur, they may include abdominal discomfort, nausea, vomiting, fever, headache, and rash or hives. Injectable vaccine: The most common side effects are redness and tenderness at the injection site; these symptoms almost always resolve within 48 hours of vaccination. Occasionally, fever, headache, and flu-like episodes have been reported. Other Potential Problems There is a rare chance that serious problems or even death could occur after receiving any medicine or vaccine. As with any serious medical problem, if the person has a significant or unusual problem after receiving the vaccine, call a doctor or bring the person to a health care provider promptly.

5 Page 5 of 5 Timing Travelers who will be receiving other vaccines in addition to typhoid should allow a month or more before travel for scheduling the vaccines to achieve best results. Oral vaccine: This vaccine is given in a 4-dose, every-other-day series on days 0, 2, 4, and 6. Each dose consists of a single capsule. Each dose shoudl be taken 1 hour before a meal with cool or lukewarm water (no warmer than body temperature). The capsules should not be taken with milk or alcohol. Capsules should be kept refrigerated. The 4-dose primary series should be completed at least1 week before arrival at high-risk areas. The booster series (also consisting of 4 doses) is recommended every 5 years under conditions of repeated or continuous exposure. Chloroquine, mefloquine, and Malarone (atovaquone/proguanil), drugs used to protect against malaria, can be taken at the same time as oral typhoid vaccine. If the traveler will be taking proguanil (a drug used alone in some countries to protect against malaria): he or she must wait at least 10 days after the final dose of oral typhoid vaccine before beginning this drug. The dosage of proguanil when used alone for malaria prevention is 200 mg per day. However, when Malarone (atovaquone/proguanil) is taken for malaria prevention, the proguanil component occurs at a lower dose (100 mg per day); therefore, Malarone may be taken at the same time as oral typhoid vaccine. Anti-bacterial drugs should be avoided for 7 days before the first dose of oral typhoid vaccine and for 7 days after the fourth dose. Oral typhoid vaccine can be given at the same time as or at any time before or after other live vaccines and immune globulins. Injectable vaccine: The primary vaccination is given in a single intramuscular injection. This vaccine should be given at least 2 weeks before arrival at a high-risk area. The booster dose, recommended every 2 years under conditions of repeated or continuous exposure, is also a single injection. Injectable vaccine can be given with other vaccines and drugs, including antibiotics or antimalarials. Shoreland, Inc. All rights reserved.